It takes some time and practice to master the basic knowledge of trigonometric functions. Here are some suggestions:

1. Understand the definition and properties of trigonometric functions, such as sine, cosine and tangent.

2. Learn how to use the unit circle to solve problems.

3. Remember some commonly used formulas, such as sin_θ+cos_θ= 1, tanθ=sinθ/cosθ, etc.

4. Practice doing some examples to deepen the understanding of trigonometric functions.